1. Laboratory of Atmospheric and Space Sciences; University of Colorado Boulder; Boulder Colorado USA
2. Space Sciences Laboratory; University of California; Berkeley California USA
3. Swedish Institute for Space Physics; Uppsala Sweden
4. CNRS, Institut de Recherche en Astrophysique et Planétologie; Toulouse France
5. Institut de Recherche en Astrophysique et Planétologie, University Paul Sabatier; Toulouse France